At the Banjacito bank Atm next to the boat yards is a great place to get Pesos. When the peso was 18-1, 3 weeks ago I got 17.95-1, the atm fee was 18.55. (with a Capitol 1 debit account) Best place to get Pesos these days. The Citibanamex atms in town haven't been working for 6 weeks now. All the other bank atms charge 80+ pesoa to use them and try to give you a poor exchange rate.
Yesterday at Banorte I got 17.18 and at that moment the mid market rate (what you see as the exchange rate on line) was 17.21. The mid market rate had been falling and the rates at the ATM's only update a couple times a day so this time it worked in my favor.